Electric arc furnaces that can be continuously charged with scrap and from which molten steel can be semicontinuously tapped are known in the iron and steel industry. In these furnaces, the charge can be fed continuously by means of a conveyor belt, a revolving drum or buckets. When buckets are used, they are often filled with scrap in a separate area and transported to the furnace in a semicontinuous charging mode called "batch charging." It is also known to use multiple furnaces or melt zones for continuous charging in an efficient manner, as in U.S. Pat. No. 5,602,867 to Hubers et al., U.S. Pat. No. 3,783,169 to Newhall, and U.S. Pat. No. 3,379,815 to Parker.
These known electric arc furnaces which operate with a continuous scrap supply either tilt or use tilting devices to completely empty the furnace vessels between heats. A tiltable arc furnace that tilts in one direction to pour molten charge and in the opposite direction to remove slag is shown in U.S. Pat. No. 2,886,617 to Sorg et al. Tilting furnaces are also shown, for example, in U.S. Pat. No. 5,462,259 to Guido and U.S. Pat. No. 2,783,990 to Tripmacher et al.
One limitation of the technologies currently available for continuous melting is that scrap in the bottom part of the furnace is always in contact with the molten steel to be tapped, and therefore the overlying molten, refined steel layer may be polluted by the underlying scrap being melted. This can lead to off-specification product. Another limitation is that the composition and the temperature of the molten steel to be tapped cannot be accurately monitored, which also can cause quality problems. A third limitation is that the melting zone and the refining zone are full of solid and incompletely melted scrap which can clog the tapping hole and spill molten steel with the attendant loss of time and energy. To overcome these problems, the process must be temporarily stopped and the melting operation must be turned off in order to tap the molten steel. What is needed to overcome these deficiencies is a furnace with vessels which can be continuously charged and then tapped from side to side without interrupting the charging and the melting of incoming charge, and without emptying the entire furnace vessel between heats.